Impaired flow through the mitral orifice in diastole is frequently encountered in patients with IHD, hypertension, cardiomyopathies and type II diabetes. The authors examined 40 type I diabetics, age 26 +/- 5.5 years, with a duration of diabetes of 15.8 +/- 7.5 years. The control group was formed by 40 non-diabetic patients comparable as to age and sex. 7.5 years. The control group was formed by 40 non-diabetic patients comparable as to age and sex. During Doppler echocardiography the ratio of early and late peak flow velocity through the mitral orifice (A/E) was evaluated and the time of isovolumic relaxation of the left ventricle (IVRT). The investigated values of A/E and IVRT were higher in diabetics than in controls (p < 0.001). Diabetics with positive microalbuminuria had higher A/E and IVRT values than diabetic with normal microalbuminuria. No relationship was found with the duration of diabetes but there is a relationship of the investigated values and compensation of diabetes (p < 0.05). At a check-up examination after six months no change of the investigated parameters was observed. The authors assume that Doppler echocardiography could become in future a non-invasive method for assessment of late complications of diabetes.